Getting reflection captures to capture movable objects

I have the exact same problem as this post here back in 2014, but the thread died off without any solutions.

I currently have a movable door that leads to another room, and a shiny wall on the opposite side of the door that reflects the doorway, but not the door itself, so that if the player looks at the wall, they can see into the next room because the movable door (which is currently not moving because it’s closed) is not captured in the reflection capture. How can I capture the door in the reflection capture so that the player can’t see straight through the door into the next room? (Just to be clear, I do not want to have the reflection capture capture dynamically, just want to have it capture twice (once when the door is closed, once when it is fully open), and have the movable door contained in the reflection).

Moveable meshes and lights aren’t captured in cubemaps. One thing you might be able to do, and I haven’t tested this, is have a static door in the scene that is hidden in game. It should be picked up in the cubemap then, but not be visible in the level once you play it.

Make that door static and then change mobility with c++ code.